Patent GB-625424-A (GB)
Title: Improvements in or relating to welding electrodes
IPC: B23K35/04
Filed: 1946-04-30
Abstract: 625,424. Making welding-rods. NATIONAL CYLINDER GAS CO. April 30, 1946, Nos. 13001 and 13002. Convention dates, May 3, 1945, and April 8, 1946. [Classes 83 (ii) and 83 (iv)] An arc welding electrode forming an arc enclosed by an inverted crucible for manual or automatic welding, has a metal core provided with a number of longitudinal ribs forming grooves to contain a sheath of flux which also overlies the ribs, a spiral conductor wound round the core and exposed continuously or at spaced points at the surface of the sheath to conduct current to the core, the contacts of the conductor with the ribs being spaced apart longitudinally of the core not less than 1/3 the diameter of the core across the ribs to afford sufficient continuity of flux around the electrode to permit the crucible to be formed round the arc. In another form the spiral conductor is dispensed with, the ribs being formed at intervals with lugs extending through the flux coating. The core 27 is formed with ribs 30 providing grooves 31, the depth or radial distance of which from the bottom of the grooves to the circumference of a circle defined by the outer edges of the ribs being .3 to .6 of the value # Dm/N where the number of ribs ranges from six for a # inch electrode to ten ribs for a inch electrode, where N is the number of ribs and Dm is the mean diameter of a circle having the same cross-sectional area as the ribbed core. When the number of ribs is increased, the ribs being thinner, the depth of the grooves is between .3 and .6 of # Dm/N x T, where T is the ratio between the depth of the ribs and the thickness thereof taken at the mean circumference. At least half the metal is within the solid part 33 of the core. The peripheral area of the core is between one and a quarter and twice the circumferential area of an equivalent plain rod. The space for at least 30 per cent of the total flux volume lies within the circle defined by the outer edges of the ribs. One or more spiral conductors 32 may be wound on the core, the turns of which are spaced longitudinally between one third and three times the maximum cross-sectional dimension of the core and of substantially the same thickness as the layer of flux at the ribs, so that the conductor is exposed on the periphery of the electrode throughout or at the points of contact with the ribs and is enclosed in flux between the ribs, Fig. 5. The ratio of the diameter of the conductor to the mean diameter of the core is from .16 for a “ inch electrode to .1 for a # inch electrode. The ends of the conductors are spotwelded or soldered to the core, and spot-welding of the conductors to the ribs is effected at intervals. The ratio of the cross-sectional area of the sheath to the cross-sectional area of the core and conductors is between .75 for flux with high mineral content such as iron or magnesium oxides, feldspar, mica, &c., with sodium silicate as binder, and 2 for a flux with relatively low mineral content, such as paper pulp or wood pulp or other cellulose material together with titanium oxide, asbestos and sodium silicate as binder. The conductors are wound on the core so as to prevent slipping of the strands longitudinally of the core. This may be effected by winding under high tension so as to notch the rib or conductor or both, or the notches may be produced by radial pressure of a shoe or roller, or by drawing the core through a die after applying the conductor, the drawing die being capable of rotating at a rate synchronized with the longitudinal movement of the core. Another form of electrode may have ribs and grooves of the same radius of curvature, Fig. 17, the depths of the grooves being equal to the diameter of the small circles 52. In a further form, Fig. 19, the depth of the grooves is .6 of the value # Dm/N. In another form, the spiral conductor N is dispensed with, the ribs being formed with projections or lugs 40, Figs. 11 and 12, to extend through the flux coating, the grooves being formed with transverse serrations to anchor the flux. The lugs may be formed during the rib-forming operation by recessed set-forming rolls or by pinching the ribs after formation.